In order to prevent the use of a weapon by unauthorized persons, it is known to provide a sensor on the handle of the weapon to receive an identification code. One example of such a sensor is a fingerprint reader. Since input of the identification code takes a certain amount of time, such a weapon is not suited for use in a dangerous situation.
Alternative systems are known, wherein the user of the weapon carries an identification mechanism, such as a wristband, a wristwatch, a ring, gloves or the like, which is compatible with the sensor to read-in the identification code. The identification code can be, for example, a PIN code or a fingerprint pattern. The authorized user of the weapon, for example a policeman, inputs the identification code into the identification mechanism at a suitable time, such as the beginning of his shift. After a positive identification code comparison, the transmitter of the identification mechanism signals the receiver in the weapon, and the weapon is enabled to fire.
To maintain the readiness of the weapon to fire, the identification mechanism transmitter continuously communicates with the receiver via a coded signal, for example, a frequency-modulated signal. In such a situation, it is only possible to fire a shot while the signal is communicated. The communication medium can be radio, ultrasound or infrared (compare U.S. Pat. No. 5,062,232, U.S. Pat. No. 5,168,144, U.S. Pat. No. 5,461,812, WO98/04880, WO00/49360, WO00/55562, WO00/65291, WO01/18332, DE 43 03 333A1).
However, in these systems, communication between the transmitter and receiver can be paralyzed by a third party. For example, a criminal using a strong interfering transmitter can interfere with the signal, and thus disable the weapon from firing. Other problems occur also. For example, during an action by the police or other security forces, a policeman cannot use the weapon of a colleague, which could be necessary if the policeman runs out of ammunition or if the colleague is injured.